Smart cards, or circuit cards, have one or more integrated circuits embedded in a card, the card having an active face with a plurality of pads that connect to the integrated circuit. A common arrangement includes eight pads arranged in four columns and two rows. An electrical connector for connection to the cards is commonly mounted on a circuit board and enables connection of the card pads to a read/write circuit. Such connectors commonly include an electrically insulative support or frame having an upper face, and a series of contacts with engaging ends projecting above the upper face. Each contact is resilient so its engaging end can be depressed to a height substantially flush with the surrounding frame upper face. Of course, a frame can be in any orientation, as where the xe2x80x9cupperxe2x80x9d face faces downwardly and the contact engaging ends project below the face.
A card may be slid in a longitudinal horizontal direction parallel to the plane of the frame upper face to engage the contacts. The card may instead be moved down or pivoted down against the frame upper face and therefore against the contacts. Many card connectors include an electrical switch for detecting the presence of a card as it approaches a fully inserted position. Such a switch can make or break a switching circuit.
One type of switch includes a special actuator that is deflected by a card so the actuator engages a special terminal or snaps down a dome contact. Such prior art switch requires a pair of special switch blades whose shape and mounting procedure is different from the contacts that engage the contact pads of the card. Such special switch blades have separate tails that must each be soldered to traces on a circuit board. The need to manufacture two separate switch contacts, mount them on the connector frame, and solder their tails to circuit board traces, adds to the cost of the connector.
In accordance with one embodiment of the present invention, applicant adds a switch to a smart card connector at minimum cost by minimizing the number of special components and simplifying the mounting of such components. This is accomplished by providing a switch blade that is mounted on the insulative frame and that makes or breaks engagement with at least one of the contacts that are substantially identical to those used to engage the contact pads of a smart card. Only a single switch blade is necessary, and in some embodiments the switch blade is not directly connected to a trace on a circuit board, since the contacts that it engages are already constructed to be soldered to traces on the circuit board. In a common type of smart card with eight contacts, this allows six or more of the contacts to be used to carry signals and/or power.
The switch blade can be mounted in a shallow depression in the upper face of the connector frame and have a pair of branches that interact with the engaging ends of two contacts. In one arrangement, both branches of the contact blade lie above and out of engagement with the engaging ends of two contacts. The branches are depressed by a card into engagement with the engaging ends of both contacts. In another arrangement, only one of the switch blade branches is depressed by a card against a contact, while the other branch is in constant engagement with the other contact. In a normally open switch, the two branches are positioned so the engaging ends of the two contacts each are biased up against one of the branches. Then, a card that depresses the two engaging ends, depresses them out of engagement with the branches of the switch blade.
The switch blade can be of minimal length and interact with a pair of contacts in a single column. However, the switch blade can be of longer length to interact with contacts lying in different columns.
In one arrangement, the switch blade has one branch that interacts with one contact, and has another branch that extends to a side of a connector and down along the side to form a tail that is soldered to a trace on a circuit board.
The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.